Light-curable compounds, such as adhesives and bonding or filling compounds, are widely used to attach objects to surfaces or to fill gaps or other openings. Such curable compounds are generally available in a semi-solid state and are manipulated and positioned on the surface or in the gap as desired to be hardened or cured into a more solid state. Curing or hardening is generally a chemical polymerization process, which is promoted and driven by various curing conditions and factors. For example, a semi-solid compound or component thereof, maybe cured by exposure to air or to energy, such as heat or light energy.
Today, most adhesive and filling compounds are cured by exposure to light energy, particularly visible or ultraviolet light energy. The light-curing process involves directing a beam of light at a specific wavelength or band of wavelengths onto a semi-solid light-curable compound to cure the compound. Such a compound typically includes light-sensitive, chemical components, which, when exposed to light at the specific wavelength, generally polymerize to harden the compound to bond, fill, or coat the work surface.
Light-curable compounds are particularly widely used in dental procedures. Dentists use light-curable dental compounds for dental repairs in a variety of tooth related applications including use as a base, a liner, a coating, a surface seal, a filling for caries and cavities, and a bonding material to secure crowns, orthodontic appliances or other dental structures to a tooth surface. Generally, visible light in the blue range of the light spectrum will be sufficient to cure most commonly used dental compounds. Once cured, such a dental compound may function, for example, to reduce further tooth decay, to provide bonds for dental structures, or to provide additional structural support to a tooth. Generally, curing is effected by various instruments or devices capable of generating the curing light, for example, a beam of blue visible light, and directing this light onto a light-curable compound manipulated on the surface of a tooth. The curing light either penetrates into the compound layer on the tooth surface for complete curing or initiates a curing reaction near the surface of a compound that propagates into the compound to cure it. The duration of the exposure to light for proper curing of the compound layer depends upon the light-curable compound itself, the thickness of the compound layer, and particularly, the power and characteristics of the light emitted from the light-generating instrument. For example, curing a compound to provide a thin tooth surface coating or veneer might require less light energy, while curing a compound to provide a thicker, deeper filling for gaps, such as caries and cavities, might require a greater amount of light energy generally provided by a stronger, more powerful light-emitting device, an increase in light intensity, or longer curing times.
There are many different forms of light-generating instruments available to the operator, such as a dentist, for curing applications. A number of these light-generating instruments are powered electrically by energy sources external to the instrument. For instance, U.S. Pat. No. 4,398,885 discloses a dental handpiece for use in dental applications. The handpiece may be used as a light source provided by a bulb. The bulb in the handpiece is powered electrically by two pins at the end of the handpiece, which must be plugged into a connecting electrical socket, typically in the wall of the operator's office.
U.S. Pat. No. 4,385,344 discloses a light source with a tungsten halogen lamp used to cure light-curable compounds, particularly for use in dental applications. Here, the light source is connected electrically through electrical leads or circuit leads that must be plugged into a separate power supply unit.
U.S. Pat. No. 5,003,434 discloses a hand-held spot source of illumination suited for use by health professionals including dentists. This hand-held unit is electrically powered by electrical leads that must be plugged into an electrical source external to the unit itself, typically an outlet in the wall of the office in which the instrument is used.
A significant drawback in the use of such light-generating instruments is that the source of electrical power is the inconvenience of connecting the instrument to an electrical outlet and the inconveniences of the electrical cables needed to deliver power to the curing instruments. Battery operated instruments have been proposed, but the weight of batteries needed to operate and cool conventional curing instruments renders many of them inconvenient.
Thus, there is a need to provide a light-generating instrument that is effective, is convenient to use and operate and is low in cost.